A general problem in networked computer systems is to keep control of data in such a way that the creator or owner of such data can determine who may use the data for which purpose. Security solutions for complex event processing systems provide confidentiality of data, authorization of network participants as well as encryption of event data. In particular, public key infrastructures are applied to complex event processing (CEP) systems using a publish/subscribe architecture in order to provide confidentiality of data, authorization of network participants as well as encryption of event data.
In some existing CEP systems, a problem arises when data being used is gathered from large quantities of external entities and people with no relationship to the organization using the data. For example, in upcoming initiatives such as Smart Cities, large quantities of data are gathered from various sources such as public infrastructures and private data (e.g., households' energy and water consumption, location data, or shopping behavior). The scale of such systems makes it very hard to implement a scheme where citizens and other third parties can explicitly determine how their private data being gathered from their homes is to be utilized, and prevent the misuse and access from unintended entities.